ABSTRACT: The procedures for the purification of a commercial chitosan as a hydrochloride and in the neutralized form are described. By applying these procedures, pure chitosans of low ash contents are obtained as determined by thermogravimetry. The agreement between the values of degrees of acetylation determined by conductimetric titrations (<img width=32 height=32 src="http://img/fbpe/po/v8n4/8292s4.gif" align=absmiddle > or = 23,0%) and by ¹H nmr spectroscopy (<img width=32 height=32 src="http://img/fbpe/po/v8n4/8292s4.gif" align=absmiddle > or = 23,6%) is very good. Chitosan hydrochloride being soluble in pure water allows the determination of intrinsic viscosity in dilute acid-free aqueous solutions and makes easier the comparison of chitosan and other polyelectrolytes with respect to their chain rigidity/flexibility.
Chitosan hydrochloride; purification; degree of acetylation; intrinsic viscosity; acid-free aqueous solutions; Huggins constant
